Fig. 1 in Recent advances in polyphenol oxidase-mediated plant stress responses

Fig. 1. Schematic diagram of plant polyphenol oxidase (PPO) gene and the mechanism for gene expression regulation. (a) The conserved PPO gene family domains. Neighbouring untranslated region (UTR, indicate in white), typical coding regions (orange) of PPO containing an N-terminal transit peptide (cTP, indicated in green), a dicopper centre CuA and CuB (blue) and the C-terminal domains (DWL motif and KFDV motif, shown in red). (b) Several players involved in the regulatory mechanism that controls PPO action upon stress, including elements of the promoter, transcription factor and microRNAs (miRs), were recently identified in a series of plants species. The MnMYB3R, miR528, miR1444, miR12112 and miR058 come from mulberry, banana, Populus trichocarpa, Salvia miltiorrhiza and grapevine, respectively. Rectangles denote the PPO gene and mRNA sequences. The ellipse represents the gibberellic acid (GA) response element (GARE) residing in the promoter region in pineapple, solid red circles represent GA, the dotted red curve shows that GA induced promoter activity through GARE by an as yet unknown mechanism. The hexagon represents the MYB-binding cis-element MSA, the black solid circle represents the transcription factor mulberry MnMYB3R. The triangle shows target sites of miR528 at the 5′-UTR of banana PPOs. The arrows indicate activation; the bars indicate inhibition. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)